<!-- index.html -->
<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="utf-8">
    <title>alert demo</title>
	</head>
  <body>
    <script>

     function judgeInternetExplorer() {
         var browser = navigator.appName;
         var b_version = navigator.appVersion;
         var version = b_version.split(";");
         if (version.length > 1) {
                 var trim_Version = parseInt(version[1].replace(/[ ]/g, "").replace(/MSIE/g, ""));
                 if (trim_Version < 9) {
                     alert("快升级你的IE")
                     return false;
                 }
             }
             alert(true)
             return true;
         }

       judgeInternetExplorer()
    </script>
  </body>
</html>
